马有福，岳荣，郭雪岩，王治云，杨斌，杨丽娟.水平布置水下排气管倒流界限试验及分析[J].内燃机工程,2017,38(2):101-106.
水平布置水下排气管倒流界限试验及分析
Experiment and Analysis of Water Backflow Mechanism of Horizontal Exhaust Pipe Under Water
DOI：
关键词:内燃机  船用柴油机  气液两相流  气液逆向流动极限  水下排气  水倒流
Key Words:IC engine  marine diesel engine  gas liquid flow  counter current flow limitation  submerged exhaust  water backflow
基金项目:
作者单位
马有福，岳荣，郭雪岩，王治云，杨斌，杨丽娟 上海理工大学 能源与动力工程学院，上海 200093 
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摘要:为防止水下排气柴油机发生海水倒灌事故，对水下排气管内发生水倒流的条件及影响因素进行了试验和分析。由水平管内气液逆向流动特性研究现状分析，指出气相惯性力与液相重力的相对大小是排气管内水倒流发生的主要物理机制。由内径90 mm水平管在3 m水深下排气的试验结果发现：防止水下排气管内水倒流发生的界限气速存在一个与管内滞留水长相关的范围，随管内滞留水长由0.3 m增至1.8 m，界限表观气速由13.0 m/s降至7.8 m/s，界限气相Wallis数由0.72降至0.55。最后以某柴油机排气参数为基础，按界限气相Wallis数等于0.60计算分析了排气管管径、排气口水位深度及排气温度等因素对管内倒流界限气速的影响，结果表明：水平管的倒流界限气速随管径增大而增大；排气口水位深度和排气温度的变化影响排气密度大小，也对排气管倒流界限气速有影响。
Abstract:An experiment and analysis of the water backflow mechanism of a submerged horizontal exhaust pipe was conducted to make marine diesel engine exhaust under water without seawater backflow accident. According to the current studies of the counter current flow limitation (CCFL), the ratio of gas phase inertial force to liquid phase gravity was the main physical mechanism of water backflow in underwater exhaust pipe. To this end, a verification test was carried out by putting an exhaust pipe with inner diameter of 90 mm in the place of 3 m underwater. Results show that：the critical superficial gas velocities in exhaust pipe to prevent water backflow is within a certain range related to the length of water remaining in exhaust pipe. With the remaining water length increasing from 0.3 m to 1.8 m, the critical superficial gas velocity decreases from 13.0 m/s to 7.8 m/s, and accordingly the critical gas phase Wallis number decreases from 0.72 to 0.55. Then, based on the exhaust parameters of a real diesel engine, the effects of the key factors such as the exhaust pipe diameter, underwater depth of exhaust outlet and exhaust temperature on the critical superficial gas velocity were calculated and analyzed according to the critical gas phase Wallis number of 0.60. Results indicate that the critical superficial gas velocity increases with the increasing exhaust pipe diameter, meanwhile, the underwater depth of exhaust outlet and the exhaust temperature also have a certain effect on the critical superficial gas velocity because they are related with the exhaust density.
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